Clarifications regarding telephone line current and Voltage

[r***@gmail.com]

I wanted to know how much current can a phoneline provide to an external
circuit both when it is off hook and on-hook w/o disrupting the working on
the line. For eg if I build a circuit that is powered from the line what
is the max current that can be drawn. Also are there any other details to
be looked into while designing such a circuit.

[r***@gmail.com]

I wanted to know how much current can a phoneline provide to an external
circuit both when it is off hook and on-hook w/o disrupting the working on
the line. For eg if I build a circuit that is powered from the line what
is the max current that can be drawn. Also are there any other details to
be looked into while designing such a circuit.

I wanna know was there a phone off hook tone that was a medium pitch buzz that went like a horn and was a steady sound and if it's still around?

[Doug McIntyre]

Post by r***@gmail.com
I wanna know was there a phone off hook tone that was a medium pitch buzz that went like a horn and was a steady sound and if it's still around?

Is the off-hook tone you are looking for the older GTE one on Wikipedia?

http://en.wikipedia.org/wiki/Off-hook_tone

[r***@gmail.com]

Post by Doug McIntyre

I wanna know was there a phone off hook tone that was a medium pitch sound that went like a horn and was a steady sound and if it's still around?

Is the off-hook tone you are looking for the older GTE one on Wikipedia?
http://en.wikipedia.org/wiki/Off-hook_tone
I made a mistake and wrote buzz instead of sound after medium pitch. I don't know if it was a siren or buzzer. I'm correcting myself.

[GlowingBlueMist]

I wanted to know how much current can a phoneline provide to an external
circuit both when it is off hook and on-hook w/o disrupting the working on
the line. For eg if I build a circuit that is powered from the line what
is the max current that can be drawn. Also are there any other details to
be looked into while designing such a circuit.

You might find this link to be of humorous interest.

http://www.sandman.com/telco.html

Quite a few telco powered devices already on the market...

[Eric Tappert]

I wanted to know how much current can a phoneline provide to an external
circuit both when it is off hook and on-hook w/o disrupting the working on
the line. For eg if I build a circuit that is powered from the line what
is the max current that can be drawn. Also are there any other details to
be looked into while designing such a circuit.

The answer, for the US, is in FCC part 68 (copy of which is at:
http://www.tscm.com/FCC47CFRpart68.pdf) sections 68-312 (on-hook) and
68-314 (off-hook, titles billing protection).

Note that many other requirements must be met to attach a device to
the telecommunications network (legally, at least...)

BTW, on-hook current is a function of the switch (modern switches
current limit the loop) and loop length.

ET